As an electrophotographic color image forming apparatus in accordance with the prior art, a color image forming apparatus of the so-called tandem type has been known, in which four process cartridges for forming toner images of cyan, magenta, yellow, and black colors, one for one, are vertically stacked in parallel, virtually in a straight line. A tandem type color image forming apparatus is designed so that the developing devices of the plurality of cartridges, in which toners different in color are stored one for one are enabled to carry out the development operation roughly at the same time. Therefore, a tandem type color image forming apparatus can form an image at a high speed.
In some of the tandem type color image forming apparatuses, the plurality of process cartridges are vertically stacked in parallel (which hereinafter will be referred to as a vertical tandem type), being therefore smaller in footprint (Japanese Laid-open Patent Application B-190245).
To define a tandem type electrostatic image forming apparatus, it is an image forming apparatus for forming an image such as a color image, which comprises a plurality of electrophotographic image forming means (stations) stacked in parallel in the direction parallel to the direction in which the intermediary transfer member or electrostatic transfer belt is moved.
A vertical tandem design, however, is likely to make the apparatus taller. In recent years, on the other hand, demand has been increasing for a personal desktop printer, and a desktop printer which can be shared by two or more persons. Therefore, a printer is desired to be minimized in height, because it is likely to be placed on a desk.
Thus, in some of the tandem type image forming apparatuses, the plurality of process cartridges are stacked in parallel in a direction that is slightly tilted relative to the vertical line (intermediary transfer member is slightly tilted) (US AA 2001055499).